I'll stick to what I'm used to: SG
----- Original Message -----
From: "Steve Gregory" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, April 27, 2010 11:19 PM
Subject: Re: [TN] Failure fatigue photos
> Hi Inge,
>
> Here's your cross section photo:
>
> http://stevezeva.homestead.com/VD0_8073_NEWXSECTION_6.jpg
>
> I haven't tried posting a picture to the IPC photo library yet, don't
> really need to, I have my own page ;^>
>
> Steve
>
> --------------------------------------------------
> From: "Inge" <[log in to unmask]>
> Sent: Tuesday, April 27, 2010 4:22 PM
> To: <[log in to unmask]>
> Subject: Re: [TN] Failure fatigue photos
>
>> Hi both of you,
>>
>> I made a job for Siemens once, about fatigue. The board behind the
>> instrument panel of a truck vibrated on the roads in South America,
>> resulting in lifted leads and the trucks became inoperable. I simulated
>> the situation in the vibrator lab, and could see clearly what happened.
>> Just as Dave told you, the crack will finally occur in a band which is
>> represented by fine structure on the one side and a coarse and elongated
>> on the other. It has partly to do with the solidification to do, fine
>> grains closest to the legs and coarser the more you are from that site.
>> I'll send one very illustrative photo. I've missed how to fix that
>> instantly. How do you bring the photos to that fast presentation URL?
>>
>> Inge
>>
>> --------------------------------------------------
>> From: "David D. Hillman" <[log in to unmask]>
>> Sent: den 27 April 2010 06:33
>> To: <[log in to unmask]>
>> Subject: Re: [TN] Failure fatigue photos
>>
>>> Hi Ioan - Do you have any optical photos of the fracture? Thermal cycle
>>> fatigue failures typically develop "banding (aka microstructure
>>> coarsening)" in the solder joint shear zone. The solder joint
>>> microstructure evolves into distinct grains of tin and lead which shows
>>> up
>>> better in optical photos. The fracture in your photos appears to be
>>> fatigue but its hard to see the microstructure in your photos. I added a
>>> photo of what typical thermal cycle induced SnPb coarsening looks like
>>> on
>>> the IPC Photo Gallery.
>>>
>>> http://ipc-technet.groupsite.com/gallery/13118
>>>
>>> Dave Hillman
>>> Rockwell Collins
>>> [log in to unmask]
>>>
>>>
>>>
>>> Ioan Tempea <[log in to unmask]>
>>> Sent by: TechNet <[log in to unmask]>
>>> 04/27/2010 07:59 AM
>>> Please respond to
>>> TechNet E-Mail Forum <[log in to unmask]>; Please respond to
>>> Ioan Tempea <[log in to unmask]>
>>>
>>>
>>> To
>>> [log in to unmask]
>>> cc
>>>
>>> Subject
>>> [TN] Failure fatigue photos
>>>
>>>
>>>
>>>
>>>
>>>
>>> Dear Technos,
>>>
>>>
>>>
>>> It looks like, for the first time, I have the occasion to look at
>>> fatigue
>>> failed joints. The lab analysis we've got states this, but does not
>>> abounds in details.
>>>
>>>
>>>
>>> One of the conclusions is "the crack propagates around harder Sn
>>> shearing
>>> the softer Pb, but the Sn and Pb zones seem fairly large for regular
>>> solder structure". Citing from Klein Wassink "During cyclic plastic
>>> deformation the microstructure inside the material changes in the zones
>>> where the deformation is concentrated. This leads to local grain
>>> growth..."
>>>
>>>
>>>
>>> I have deposited the micro-sections on the IPCs website
>>> http://ipc-technet.groupsite.com/gallery/13116
>>>
>>>
>>>
>>> I would need your expert opinion regarding the failure. Is this fatigue?
>>> The big pure Sn and pure Pb areas, are they normal size for fatigued
>>> joints?
>>>
>>>
>>>
>>> Thanks,
>>>
>>>
>>>
>>> Ioan Tempea, ing.
>>> Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
>>> T | 450.967.7100 ext.244
>>> E | [log in to unmask] <mailto:[log in to unmask]>
>>> W | www.digico.cc <http://www.digico.cc/>
>>>
>>>
>>> N'imprimer que si nécessaire - Print only if you must
>>>
>>>
>>>
>>>
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